While the US is most likely to reach COVID-19 herd immunity in the third or fourth quarter of 2021, it could come as early as the second quarter of 2021, if vaccines are highly effective and launched smoothly, or if significant cross-immunity is discovered in a population. But if early vaccine candidates have efficacy or safety issues, the pandemic could extend until 2022 or later.
To read the article, see “When will the COVID-19 pandemic end?,” September 21, 2020.